The period between the wars brought the culmination of Canada's growth to
independent nationhood within the British Commonwealth. Prime Minister Borden had been
included in the Imperial War Cabinet in London. He piloted through the Imperial Conference
of 1917 a resolution that the dominions "should be recognized as autonomous nations
of an imperial commonwealth." To both the 1919 Peace Conference and the League of
Nations Canada sent its own delegates. The Imperial Conference of 1926 confirmed in its
Declaration of Equality that the United Kingdom as well as the dominions had become
"autonomous Communities within the British Empire, equal in status, in no way
subordinate one to another." They were, however, "united by a common allegiance
to the Crown, and freely associated as members of the British Commonwealth of
Nations." These resolutions were confirmed by the British Parliament in 1931 in the
Statute of Westminster.

The statute provided that no law passed in the future by the United
Kingdom should extend to any dominion "except at the request and with the consent of
that Dominion." Canadian sovereignty thus had been achieved by a long process of
peaceful constitutional evolution. This was vividly demonstrated by the independent
decision of its Parliament that Canada enter World War II at the side of Britain, which it
did within a week of the outbreak of hostilities in September 1939.